Fluorescence Modulation of Conjugated Polymer Nanoparticles Embedded in Poly(N-Isopropylacrylamide) Hydrogel

A series of conjugated polymers (CPs) emitting red, green, and blue (RGB) fluorescence were synthesized via the Suzuki coupling polymerization. Polymer dots (Pdots) were fabricated by the reprecipitation method from corresponding CPs, in which the Pdot surface was functionalized to have an allyl moiety. The CP backbones were based on the phenylene group, causing the Pdots to show identical ultraviolet-visible absorption at 350 nm, indicating that the same excitation wavelength could be used. The Pdots were covalently embedded in poly(N-isopropylacrylamide) (PNIPAM) hydrogel for further use as a thermoresponsive moiety in the polymer hydrogel. The polymer hydrogel with RGB emission colors could provide thermally reversible fluorescence changes. The size of the hydrogel varied with temperature change because of the PNIPAM’s shrinking and swelling. The swollen and contracted conformations of the Pdot-embedded PNIPAM enabled on-and-off fluorescence, respectively. Fluorescence modulation with 20 to 80% of the hydrogel was possible via thermoreversibility. The fluorescent hydrogel could be a new fluorescence-tuning hybrid material that changes with temperature.

(E)-1-(4-Bromophenyl)-3-[3-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one

In the title compound, C27H20BrN5O, the dihedral angle between the heterocyclic rings is 10.2 (2)°. The phenyl ring bound to the triazole ring is disordered over two orientations in a 0.808 (4):0.192 (4) ratio. In the crystal, C—H...O interactions form chains along [010]. π–π interactions are observed between the phenyl–pyrazolyl unit and the phenylene group of a neighbouring molecule.

A chelating bis(aminophenol) ligand bridged by a 1,1′-ferrocene-bis(para-phenylene) linker

The 1,1′-ferrocene-bis(p-phenylene) group serves as a structural linker connecting two iminosemiquinones to palladium without significant electronic interactions between the ferrocene and the palladium complex.

(E)-N,N-Diethyl-2,6-diisopropyl-4-[2-(4-nitrophenyl)ethenyl]aniline

The title compound, C24H32N2O2, was prepared by Horner olefination of 4-diethylamino-3,5-diisopropylbenzaldehyde and diethylp-nitrobenzylphosphonate. There are two independent molecules (AandB) in the asymmetric unit. Their main axes, defined by the line connecting the N atoms of the nitro and amino groups, open an angle of 79.42 (3)°. Steric hindrance around the amino group is reflected in a long aryl C—N bond [1.434 (3) Å for moleculeAand 1.440 (3) Å for moleculeB], a pyramidal geometry [angle sum = 350.0 (2)° for moleculeAand 349.6 (2)° for moleculeB], and dihedral angles between the phenylene group and the plane defined by the CH2—N—CH2unit of 86.9 (3)° for moleculeAand 88.3 (3)° for moleculeB. This gives structural support for the electronic decoupling of the amino group from the nearly planar nitrostilbene moiety (r.m.s. deviation for C, N and O atoms = 0.097 for moleculeAand 0.107 Å for moleculeB).